Current heater duty report?

DocTrucker

Any way to get the current heater duty from the Duet v0.6?

I'm considering using and arduino to report this but a gcode command to get the report would be much easier!

droftarts

Does one of the M408 reports do it?

Ian

dc42

https://duet3d.dozuki.com/Wiki/Gcode#Section_M573_Report_heater_PWM

DocTrucker

Thanks. M573 did the trick although the JSON reports do look interesting. I will familiarise myself with them for another time!

End result is standard E3D cartridge is running at 100% duty and struggling to reach 230C when the part cooling fan is on. It's around 94% after reaching temperature about 3 minutes ago. Alas it appears I need to revisit my fan duct a little.

Did see some nice CFD renderings in Daresbury today. Apparently a full car simulation was about £200 worth of computer time. Needless to say file prep etc would have taken that significantly higher! I wonder what poor man's CFD tools are kicking about in the open source world for simple simulation on desktops?

DocTrucker

@dc42 the quote in the documentation is weirdly vague about the period of the duty:

This gives a running average (usually taken over about five seconds) of the PWM to the heater specified by the P field. If you know the voltage of the supply and the resistance of the heater this allows you to work out the power going to the heater. Scale: 0 to 1.

Is there any way to adjust the period of this measurement? Can that be a feature request or is this rolling-average value used in the control loop?

dc42

@DocTrucker said in Current heater duty report?:

End result is standard E3D cartridge is running at 100% duty and struggling to reach 230C when the part cooling fan is on. It's around 94% after reaching temperature about 3 minutes ago. Alas it appears I need to revisit my fan duct a little.

Check that there is a gap of about 2mm between the top of the heater block and the bottom of the heatsink.
Use a silicone sock over the heater block.
Make sure that the part cooling fan directs air at the print below the nozzle, not at the heater block.
Make sure you are not using a 24V heater cartridge on a 12V system.

Is there any way to adjust the period of this measurement? Can that be a feature request or is this rolling-average value used in the control loop?

You are the first person I have heard of using this M-code, so I don't plan to make it configurable. You could of course change it if you build the firmware yourself. Why do you want to change it?

DocTrucker

@dc42 get a better idea of what the system is doing when the heater is in an oscilating loop. If there's not been much call for it so far no problem. I was using ot to see if the tuning was at fault. If it's running at 100% then obviously not!

Yeah all are ok and I am aware the weakness is in part cooling duct. Directing a large volume of air isn't an exact science until you can afford it!